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Old 24-08-2012, 10:18   #106
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Re: Hmmmm - Bowthrusters ??

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Originally Posted by Nibiruwayne View Post
Interesting comments. If everyone agreed we'd all own the same boat. Different strokes for different folks. Everything in sailing likely holds advantages and disadvantages.
The one issue not discussed is hull weakness from an installation. I would worry about a collision with or without watertight bulkheads.
Any thruster is mounted in the forepeak which has a watertight bulkhead aft. no one would entertain having one fitted otherwise.

Secondly the thruster comes with a moulding either tubular or a compartment with the origional hull as the bottom/door. Look at the picture posted.

When we arrived here in Croatia most of the charter fleet were being prepped for the sailing season, MOST had thrusters fitted and Most were of the tube design.

Weakness is not a consideration as it tends to more strengthen the area. The seal for control cables is no more than having a sumlog fitted, just another skin fitting..
Cheers Frank
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Old 24-08-2012, 10:51   #107
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Re: Hmmmm - Bowthrusters ??

There are lots of boats in this thread that don't have watertight bulkheads. To retrofit a watertight bulkhead would be impractical, expensive and likely not doable for lots of boats. I agree a watertight bulkhead aft of the 'tube' is necessary. Further a retrofitted glassed in tube would not have the Se integrity as a well planned design with the tube faired into the hull. Just my opinion.
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Old 24-08-2012, 10:57   #108
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Re: Hmmmm - Bowthrusters ??

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There are lots of boats in this thread that don't have watertight bulkheads. To retrofit a watertight bulkhead would be impractical, expensive and likely not doable for lots of boats. I agree a watertight bulkhead aft of the 'tube' is necessary. Further a retrofitted glassed in tube would not have the Se integrity as a well planned design with the tube faired into the hull. Just my opinion.
The tube is always retro fitted, very very few manufacturers fit thrusters from the outset. Other than Europe BUT still it's a kit form with heavily layed tube/box.....

Cheers
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Old 24-08-2012, 11:15   #109
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Re: Hmmmm - Bowthrusters ??

I imagine dragging a couple of buckets effects a 60 footer alot less than a 40 footer....
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Old 24-08-2012, 11:35   #110
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Quote:
Originally Posted by Cheechako
I imagine dragging a couple of buckets effects a 60 footer alot less than a 40 footer....
No BT on my 46 footer, but I do have a couple of buckets.

I always thought of a bow thruster as a temporary solution for someone who needs a better slip.
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Old 24-08-2012, 11:43   #111
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Re: Hmmmm - Bowthrusters ??

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Originally Posted by Lagoon4us View Post
Any thruster is mounted in the forepeak which has a watertight bulkhead aft. no one would entertain having one fitted otherwise.
I've never seen a thruster mounted ahead of a watertight bulkhead. Maybe in a Sundeer.

My boat has elaborate anti-collision provisions -- Kevlar hull forward of the keel, watertight bulkhead to the forepeak, massive layup in the bow, etc. But the thruster is behind the bulkhead.

However, the thruster is mounted in a well with the walls well above the waterline -- a kind of cofferdam. So if something failed, the water would not pour into the bilge (bless you, Bill Dixon).

But I don't think that's very likely -- the tunnel is an integral part of the hull and quite massively laid up. The thruster has a drive leg somewhat, I guess, like a saildrive, but without the big rubber diaphragm. I think it's pretty foolproof. I've never ever heard of a boat sinking because of a problem with a bowthruster.
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Old 24-08-2012, 11:53   #112
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Re: Hmmmm - Bowthrusters ??

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Originally Posted by Lagoon4us View Post
The tube is always retro fitted, very very few manufacturers fit thrusters from the outset. Other than Europe BUT still it's a kit form with heavily layed tube/box.....

Cheers
Like you say, maybe it's different in Europe. Over here, I think most boats over 45 feet are designed with bow thrusters, and you would have a hard time buying a new boat over 50 feet without one. The bow thruster tunnel is designed in from the start and the tube is part of the original hull build -- no retrofitting. I don't know how it's done in the States.

But even retrofitted bow thrusters in boats not designed for them ought to be plenty strong enough. It's not rocket science to whack a couple of holes in the hull at the bow and tab in and glass in a fiberglass tube. I would guess that the hull ends up a bit stronger afterwards as you've added a structural member.
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Old 24-08-2012, 11:53   #113
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Re: Hmmmm - Bowthrusters ??

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I've never seen a thruster mounted ahead of a watertight bulkhead. Maybe in a Sundeer.

My boat has elaborate anti-collision provisions -- Kevlar hull forward of the keel, watertight bulkhead to the forepeak, massive layup in the bow, etc. But the thruster is behind the bulkhead.

However, the thruster is mounted in a well with the walls well above the waterline -- a kind of cofferdam. So if something failed, the water would not pour into the bilge (bless you, Bill Dixon).

But I don't think that's very likely -- the tunnel is an integral part of the hull and quite massively laid up. The thruster has a drive leg somewhat, I guess, like a saildrive, but without the big rubber diaphragm. I think it's pretty foolproof. I've never ever heard of a boat sinking because of a problem with a bowthruster.
Certainly ours and others Beneteau mono's i've looked at have it fwd of the crash bulkhead but of course every boat has the right to be different, ours being a drop down is mounted in a cofferdam as well.

Agree about strength, to have a tube glassed in port to stb adds massive structural strength also.

Ours has a small motor actuating the lever arm to open the door with the prop attached the actual drive motor is huge and pushes the head away very nicely.

I smiled when i saw it on the inventory but after having to berth this high windage boat into berths so tight i love it.

The second great attribute is a cat running on one motor is very very difficult to berth, a thruster in that circumstance makes it doable.

Cheers Frank
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Old 24-08-2012, 11:56   #114
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Re: Hmmmm - Bowthrusters ??

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No BT on my 46 footer, but I do have a couple of buckets.

I always thought of a bow thruster as a temporary solution for someone who needs a better slip.
The world is full of 'bad slips' the new to me noise here is the growl of a thruster, if it gets louder/closer it certainly warrants sticking the head out the hatch hoping there's no incoming non-compus coming our way.
LOL Cheers Frank
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Old 24-08-2012, 12:20   #115
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Quote:
Originally Posted by Lagoon4us
The world is full of 'bad slips' the new to me noise here is the growl of a thruster, if it gets louder/closer it certainly warrants sticking the head out the hatch hoping there's no incoming non-compus coming our way.
LOL Cheers Frank
We're on the cap of a dock that has a lot of 80' slips, capped by five 50' slips that T-bone into a 100-footer. It's gotten so that we can identify which boats are returning to their slips by the unique growls of their thrusters. As a matter of fact, when the 100-footer comes home I can tell which captain is driving just by the sound of his thruster technique.

Life can be fun when the next slip over is occupied by a Feadship. I have to remind myself not to fall in when handling lines because their thruster could take your leg off.
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Old 24-08-2012, 12:26   #116
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Re: Hmmmm - Bowthrusters ??

Largest thrusters i have fitted to a boat were a set of Schottels, bow and stern, the tubes were 40inch diameter.

The boat was a 600 Tonne paddle-wheeler (Mississippi Queen style sternwheeler) they were electrically powered from a 300Kva genset with huge resistor banks to absorb the unused current when used intermittently.

During sea trials we were paddling ahead at 8/9 knots and pulled on full thrust to port on the forward thruster, the boat made a 20 deg heading change in a heartbeat.

Thrusters were required equipment by MSB for safe navigation in Sydney Harbour and if you have ever seen Sydney Harbour on Australia Day you'll understand what i mean.

Cheers Frank
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Old 24-08-2012, 12:29   #117
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Re: Hmmmm - Bowthrusters ??

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We're on the cap of a dock that has a lot of 80' slips, capped by five 50' slips that T-bone into a 100-footer. It's gotten so that we can identify which boats are returning to their slips by the unique growls of their thrusters. As a matter of fact, when the 100-footer comes home I can tell which captain is driving just by the sound of his thruster technique.

Life can be fun when the next slip over is occupied by a Feadship. I have to remind myself not to fall in when handling lines because their thruster could take your leg off.
It's become a feared noise for us, prior to Europe it was very unfamiliar.

Australia just isn't as cramped where i come from, many times we have sailed to our mooring there no one to worry about....
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Old 24-08-2012, 12:40   #118
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Re: Hmmmm - Bowthrusters ??

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So to your way of thinking anyone who gets a thruster on a 44ft boat can't drive......that's what your saying right....???

I am going to get in sooooo much trouble if I answer that,,,,,,,,

I have seen more stupidity in people who drive boats than you can imagine. Some of what we have seen when working on the water has had s laughing and rolling around on the floor,

do you need a bow thruster,,,, no, not on a 50 foot boat, does it come in handy sometime, YES, but necessary, IMHO NO,,,,, most are underpowered anyways to be very effective when you really need it. just because you have one does not mean you are any safer or a better boat driver. most thruster that I have seen and used on small boat were only good for 10-20 seconds of use at one time, then you had to let them cool down,
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Old 24-08-2012, 12:58   #119
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Re: Hmmmm - Bowthrusters ??

No gear makes you safer, having tools available that function assist you to do things better.

If Thrusters were not fitted to a majority of the boats in Europe then accident/damage levels would be high.

See people do dumb things on the water every day, i don't think any Italian has ever passed a boat by the stern, they speed up and change course just to cross your bows, maybe other parts of the world are different to yours where equipment that ' in your opinion" is not necessary but it is here...
Cheers
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Old 24-08-2012, 13:48   #120
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Re: Hmmmm - Bowthrusters ??

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I am going to get in sooooo much trouble if I answer that,,,,,,,,

I have seen more stupidity in people who drive boats than you can imagine. Some of what we have seen when working on the water has had s laughing and rolling around on the floor,

do you need a bow thruster,,,, no, not on a 50 foot boat, does it come in handy sometime, YES, but necessary, IMHO NO,,,,, most are underpowered anyways to be very effective when you really need it. just because you have one does not mean you are any safer or a better boat driver. most thruster that I have seen and used on small boat were only good for 10-20 seconds of use at one time, then you had to let them cool down,
For that matter, is an auxiliary engine really necessary in a sailboat? I sailed for about a decade without any engine at all. Sailed off and onto a mooring, docked, undocked, somehow got through traffic, sculled when there was no wind, or waited, drifting. Does that make me a great, hair-on-my-chest he-man sailor? Hell no. You make do with whatever tools you have -- that just happens to be all the tools I had at the time. I wouldn't want to go back - an auxiliary engine is an awfully handy thing, and quite a lot more than a convenience. Same with thrusters.

As to stupidity afloat -- an auxiliary engine can make up for a certain amount of lacking sailing skills. But just a certain amount. You see poor sailors with engines, and good sailors also. An engine can be a crutch for a bad sailor, or a great enhancement for a good one. Same with thrusters.
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